"The lines of a tramline are usually about 30 cm wide and 2 metres apart while the distance between tramlines can vary from 12 metres (13 yards) to 30 metres (32.8 yards)...."

PS/PS. When I first saw this creation, I thought "Sirius". Since I didn't understand why, I moved one and didn't think anymore of it. Then, after posting this, I decided to see if there were any reports offered about the formation, and read this (source) :

"The star Sirius has a strong symbolic connection with this septenary symbol. Star of the gods, sign of Light, of Isis, Toth and the Enlightened, the Star of "Bethlehem" who guides the birth of the divine kings on Earth, etc."